Wind tunnel turning vane heat exchanger

ABSTRACT

A cooling system for a wind tunnel is disclosed. The heat exchanger of the present disclosure is formed as a turning vane in an airflow duct of a re-circulating wind tunnels. The individual vanes are formed from extruded aluminum with coolant fluid channels running continually down the length of the vane. One or more channels can be used, depending on the application of vane and the cooling capacity needed. The exterior of the vanes are formed in an airfoil shape to efficiently turn the air flow the desired amount in a manner well known in the art. The turning vanes are connected to a fluid supply with single piece connectors that removably attach to the turning vanes. In the depicted embodiment the connectors are attached with screws. In the depicted embodiment the connectors are formed as a single piece in a two-piece injection mold.

CROSS REFERENCE APPLICATIONS

This application is a continuation of application Ser. No. 14/942,086filed Nov. 16, 2015, which is a divisional application of U.S.application Ser. No. 13/520,616 filed Jul. 5, 2012, which is a NationalStage application of PCT/US2011/021437 filed Jan. 1, 2011, which claimsthe benefit of provisional application No. 61/295,229; filed Jan. 15,2010, all of which are hereby incorporated by reference for allpurposes.

BACKGROUND

Wind tunnels have many uses, including research and as training devicesand/or amusement rides that allow a person to simulate freefallskydiving. Wind tunnels have two broad types, open flow andre-circulating. Additionally wind tunnels can be oriented vertically orhorizontally, that is with the airflow in the test section or flightsection going generally parallel to the ground or generally verticallyupward. Generally, only wind tunnels that are going to be used tosimulate sky diving are built vertically, because building a verticaltunnel adds significantly to the expense. In any re-circulating tunnel,the direction of the air flow must be changed multiple times so thatafter one pass through the system the air ends up where it began.Turning vanes are often used for this purpose to change the direction ofair flow while maintaining the laminar nature of the air flow thusdecreasing the energy necessary to make the air turn.

Air flowing over the internal surfaces of the wind tunnel createsfriction and thus heat. If the tunnel is open-flow, that heat isautomatically ejected from the system into the atmosphere. In a closedcircuit, re-circulating tunnel, virtually all of the energy put into thesystem becomes heat. Every kilowatt of electricity used by such a tunnelcreates roughly 3414 British Thermal units of heat each hour. Some ofthese re-circulating wind tunnels use 2500 or more kilowatts ofelectricity and thus can generate more than 8 million btus of heat eachhour. In a closed circuit tunnel, this heat quickly builds to a levelthat can be unbearable for the occupants. If a person is going to be inthe air flow path, it is often necessary to remove this heat (cool theair) to ensure that person remains safe and comfortable. Cooling of theair sometimes needs to be done in research tunnels when the temperatureof the air is part of the test conditions. Furthermore, if one caneffectively capture and transport this heat to a location away from thewind tunnel where it may otherwise be needed, all or most of the energyused to operate the wind tunnel can be recycled or recaptured and thenused to heat another structure or area. Thus, properly situated next toa facility that needs the heat (such as a shopping mall or water park),the majority of the cost to power the wind tunnel can be offset by thesavings from heat recycling.

One method that has been used to cool the air in a re-circulating windtunnel is to insert a cooling coil into the airflow and connect thatcoil to an external chiller. The heat transfers through the walls of thecoil to a fluid or other medium inside the coil. The medium is thenpumped to another location where the heat can be removed from themedium. Unfortunately, these prior art cooling coils added a largeamount of drag to the wind tunnel (as much as doubling the total drag ofthe system) due to the additional friction caused by the passing the airover the surface of the coil. More power was also needed to overcome theadditional drag induced by the coil in the airflow. Each additionalkilowatt needed to overcome this cooling system drag then becomes moreheat needing removal. Thus, this prior art method of insertingtraditional cooling coils into the airflow is a very inefficient way tocool a re-circulating wind tunnel.

Another method used to cool wind tunnels was to embed cooling coilsinside components that, for some other reason, already existed in theairflow. One example is to insert cooling coils into the turning vanesused to change the direction of the airflow at each corner—convertingthe vanes into a large heat exchanger. Since the vanes were alreadypresent in the system, no new drag was added and thus the problem ofadding heat in order to take out heat was avoided. However, prior artturning vane heat exchangers were very expensive to build and/ormaintain, adding significantly to the cost of building and maintainingthe wind tunnel. They required a huge number of complex mechanical orwelded connections between the various tubes or pipes of the coolingcoil. Obtaining adequate heat transfer between the medium in the coilsand the turning vanes was also very difficult with such a design. It isnot clear that any turning vane heat exchangers capable of removing allof the heat generated by a wind tunnel were every successfully built.

The foregoing example of the related art and limitations relatedtherewith are intended to be illustrative and not exclusive. Otherlimitations of the related art will become apparent to those of skill inthe art upon a reading of the specification and a study of the drawings.

SUMMARY

One aspect of the present disclosure is a heat exchanger in which theheat transfer medium flows through a hollow turning vane in the windtunnel.

One aspect of the present disclosure is a heat exchanger that has vanesextruded from aluminum with screw bosses formed into the interior ofeach vane and running continuously down its length to allow simple andinexpensive attachment of the vanes to end pieces.

One aspect of the present disclosure is a heat exchanger turning vanethat connects to standard plumbing fittings.

One aspect of the present disclosure is a heat exchanger wherein theconnection to the vane from a water pipe is a single transition piecethat itself can be attached to the vane in a water tight manner withoutwelding or chemical bonding, but rather with a simple mechanicalconnection.

One aspect of the present disclosure is a transition piece that can beattached to one end of the vane with screws or other fasteners solelyfrom one side (the non vane side) of the transition piece.

One aspect of the present disclosure is a transition piece that can beattached to the heat transfer fluid inlet and heat transfer fluid outletsolely with inexpensive common plumbing components.

One aspect of the present disclosure is a heat exchanger wherein thetransition piece is made from a single piece of molded material.

The following embodiments and aspects thereof are described andillustrated in conjunction with systems, tool and methods which aremeant to be exemplary and illustrative, not limiting in scope. Invarious embodiments, one or more of the above described problems havebeen reduced or eliminated, while other embodiments are directed toother improvements.

The heat exchanger of the present disclosure is formed as a turning vaneassembly in an airflow duct or high speed air channel, such as in are-circulating wind tunnels. The individual vanes are formed fromextruded aluminum with coolant fluid channels running continually downthe length of the vane. One or more channels can be used, depending onthe application of vane and the cooling capacity needed. The exterior ofthe vanes are formed in an airfoil shape to efficiently turn the airflow the desired amount in a manner well known in the art. The turningvanes are connected to a fluid supply with single piece connectors thatremovably attach to the turning vanes. In the depicted embodiment theconnectors are attached with screws. In the depicted embodiment theconnectors are formed as a single piece in a two-piece injection mold.

One embodiment is vane array comprising a plurality of hollow vanes,each having substantially constant cross section, the vanes disposedsubstantially parallel to each other; each vane having a first end and asecond end; the array having a first edge defined by first ends of theplurality of vanes; the array having a second edge defined by secondends of the plurality of vanes; each vane's cross section defining atleast two screw bosses formed therein; each vane having at its first enda first respective connection piece, first respective connection piecesecured thereto by means of screws, each screw threadingly engaged witha respective screw boss; each vane having at its second end a secondrespective connection piece, first respective connection piece securedthereto by means of screws, each screw threadingly engaged with arespective screw boss; a first manifold disposed along the first edge; asecond manifold disposed along one of the first edge and the secondedge; and pipes connecting the first manifold, the connection pieces,and the second manifold, thereby defining a plurality of fluid flowpaths, each fluid flow path passing from the first manifold and throughat least one of the vanes to the second manifold.

The pipe connection to each connection piece defines an openingthereinto; the screw bosses formed into each vane's cross sectionincluding at least one screw boss positioned such that the screwthreadingly engaged therewith has an axis passing through the opening.

In addition to the exemplary aspects and embodiments described above,further aspects and embodiments will become apparent by reference to theaccompanying drawings forming a part of this specification wherein likereference characters designate corresponding parts in the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the heat exchanging turning vaneassembly in a re-circulating wind tunnel.

FIG. 2 is an exploded view of a single turning vane, the fluid pipes andthe connection pieces.

FIG. 3 is a side elevation view of one side of the turning vane.

FIG. 4 is a perspective view of the bottom end of the heat exchangerturning vane assembly.

FIG. 5 a perspective view of one section of one end of the heatexchanger turning vanes mounted in the frame with the fluid plumingattached.

FIG. 6 is a side elevation view of the other side of the heat exchangerturning vane assembly.

FIG. 7 is a top view plan of the connection piece.

FIG. 8 is the bottom plan view of the connection piece.

FIG. 9 is a top perspective view of the connection piece.

FIG. 10 is a cross sectional view taken along line 7-7 of the connectionpiece.

Before explaining the disclosed embodiment of the present invention indetail, it is to be understood that the invention is not limited in itsapplication to the details of the particular arrangement shown, sincethe invention is capable of other embodiments. Exemplary embodiments areillustrated in referenced figures of the drawings. It is intended thatthe embodiments and figures disclosed herein are to be consideredillustrative rather than limiting. Also, the terminology used herein isfor the purpose of description and not of limitation.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring first to FIG. 1 , an upright re-circulating wind tunnel 100 isshown with the air flow shown in by the arrows A. This type of windtunnel is most commonly used for skydiving simulation and other humanflight activities. Other types of re-circulating wind tunnels are wellknown in the art, including ones used for various types of testing.Although the present disclosure will be discussed using the uprighttype, it is to be understood that the disclosure includes other types ofre-circulating wind tunnels. A common feature of all re-circulating windtunnels is the heat generated by the friction of the air flow throughthe plenums.

The re-circulating wind tunnel 100 can have a single returnconfiguration, as shown in FIG. 1 , or a multiple return configuration.See for example U.S. Pat. Nos. 6,083,110 and 7,156,744. A single returnre-circulating wind tunnel 100 has a first upright plenum 106 which hasflight chamber 104. The air A then flows into top plenum 105, secondvertical plenum 107 and then into bottom plenum 108 and back into firstupright plenum 106. The upright plenums 106, 107 and the top plenum 105of the wind tunnel 100 are shown dotted lines for clarity. The positionof the fans 101 is shown for purposes of example only and not bylimitation. Fans 101 in other positions well known in the art could beused as well and are considered within the scope of this disclosure.

A heat exchanger turning vane assembly 200 is in end 109 of the bottomplenum 108. Other locations could be used as well depending on theparticular application. More than one heat exchanger turning vaneassembly 200 could also be used depending on the particular application.In many instances, a second heat exchanger turning vane assembly wouldbe located below the flight chamber 104, due to the lower cost ofinstalling the assembly on the ground. However, if needed in aparticular installation, the assembly could be installed in the topplenum 105 corners.

Standard turning vane assemblies 102 can be used at the corners where noheat exchanger turning vane assembly 200 is installed to smoothly changethe direction of the air flow with minimum turbulence. A turning vaneassembly 102 is shown above the flight chamber 104 at the transitionfrom the first vertical plenum to the top plenum 105 as an example. Theother turning vanes have not been included to simplify the drawings, butmay be used in normal operation of the re-circulating wind tunnel as ahuman flight simulator.

In the depicted embodiment, end 109 of the bottom air plenum 108 has alarger width D2 than the width of the bottom air plenum D1 to allow theplumbing of the heat exchanger turning vane 200 to be out of the mainflow path to reduce air turbulence but this is not essential. Where thecooling system will be retrofitted into an existing wind tunnel, theplumbing at the end of the vanes can remain in the airflow.

FIG. 2 is an exploded view of a single heat exchanger turning vane 201with two plumbing connection pieces 202, one at each end to connect tostandard plumbing pipe with a common chemical bond or via a standardflexible hose 204 held in place with standard hose clamps. In thedepicted embodiment, the hose 204 is made of rubber, but other flexiblematerials could be used as well. FIG. 3 is an end view of heat exchangerturning vane 201. The outer surface 205 is configured according to wellknown aerodynamic principles in a curved air foil shape to smoothlychange the direction of the airflow. Arrows A indicate the airflow overthe heat exchanger turning vane 201. In the depicted example, theairflow would change direction by 90 degrees. If desired, other amountsof change of direction could be achieved. The heat exchanger turningvane 201 has a substantially continuous interior configuration andsubstantially constant cross section in the depicted embodiment, suchthat the end view would also be a cross sectional view at any pointalong its length.

The heat exchanger turning vane 201 is made by extrusion molding ofaluminum in the depicted example. Other materials with similarproperties of good thermal exchange and sufficient rigidity could beused as well. The heat exchanger turning vane 201 is hollow to reducethe amount of material required and to allow for fluid to flow throughthe length of the heat exchanger turning vane 201 such that the fluidfunctions as a heat transfer medium. The thickness of the outer wall 211is a balance between being thick enough to provide sufficient rigidityto the turning vane 201 and thin enough to allow good thermal exchangebetween the heat transfer medium flowing inside the vane and the airflowing over the outside of the vane. The air flowing over the surface205 is thereby cooled as the heat is transferred into the fluid flowinginside the vane 201. In the depicted example, water is used as thecooling fluid due to its ready availability and lack of toxicity. Thisalso allows the fluid heated by the heat exchange to be used to easilytransport the heat to other locations or for other purposes for whichwater would normally be heated by standard heating devices. Examplesinclude, but are not limited to domestic hot water use, swimming poolsor aquariums and other uses as will be discussed further below. Other,known in the art heat transfer mediums could be used as well, including,but not limited to, Freon gas, salt water, compressed gasses and otherrefrigerants.

The length of the turning vane 201 can vary depending on theapplication. Vanes as long as 65 feet or longer can be used in largeinstallations. Bracing members 209, 210 divide the interior space of theheat exchanger turning vane 201 into channels. The bracing members 209and 210 are to ensure the heat exchanger turning vane 201 has sufficientrigidity to withstand the airflow and the weight of the fluid flowingthrough in use without bending. The bracing members 209, 210 alsoincrease the surface area of the turning vane 201 that is in contactwith the fluid, increasing the speed and efficiency of the heat transferto the fluid. In the depicted embodiment there are three channels 206,207 and 208. More or less channels and bracing members could be useddepending on the size of the heat exchanger turning vane 201 and thevolume of fluid flow desired. In the depicted embodiment, all of thefluid in a turning vane would be flowing in the same direction,regardless of how many channels the interior of the vane is divided intofor structural reasons. The heat exchanging capacity depends on thesurface area of the contact between the fluid and the turning vane 201,the thermal resistance of the material of the heat exchanger turningvane 201, the thermal resistance and flow rate of the fluid and thedifference in temperature between the cooling fluid and the airflow. Forany given turning vane 201 in any given installation, these factors willall need to be optimized to ensure sufficient cooling of the airflowoccurs. In the depicted embodiment the majority of the area of the crosssection of the turning vane 201 is fluid flow space, as seen in FIG. 3 .

At ends 212 and 213 and at opposing corners of channel 207 screw bosses214 a, 214 b are formed into the interior of the heat exchanger turningvane 201. These screw bosses 214 a, 214 b allow the turning vane 201 tobe attached to a flange or other surface perpendicular to the directionof flow of the fluid in the vane. This method of attachment makes theassembly of turning vane assemblies 200 faster, easier and lessexpensive. Since the screw bosses can be formed into the extrusion moldfor the turning vane 201, the turning vane 201 can be extruded to anylength and then attached as needed with no further modification needed.Since the screw bosses 214 a, 214 b are formed inside the heat exchangerturning vane 201, the method of attachment to whatever transition pieceor end plate does not disrupt the airflow over the turn vane, as inprior art methods of attaching turning vanes to support racks. If theattachment points were on the outer surface (airflow surface) of theturning vane 201 such extrusion molding could not be used, since thenthe attachment points would be on the entire surface of the turning vane201, spoiling the aerodynamic qualities needed.

In an alternate embodiment the screw bosses 214 a, 214 b could be formedby leaving the area of the screw bosses solid in the extruded part anddrilling out holes and possibly tapping threads after extrusion to formscrew bosses 214 a, 214 b. In another alternate embodiment the screwattachments could be installed into the interior of or on the exteriorof the turning vane after formation of the turning vane, such as bywelding, epoxy or other means.

In a heat exchanger turning vane assembly 201 it is necessary that theattachment of the turning vane to the connection piece 202 be largelyfluid tight, to allow for continuous flow of fluid, often underpressure. Depending on the application and the heat exchange mediumbeing used, some low levels of leakage of exchange medium may beacceptable. Therefore the term fluid tight should be understood toencompass levels of fluid leakage at the junctions that are withinoperating tolerances. However, even once the screw bosses 214 a, 214 bare formed into interior of the turning vane 201, a connection piecethat allows for a fluid tight connection that is easy to assemble and isnot expensive to manufacture is needed. Large numbers of theseconnection pieces are needed, as will be discussed below. The greatestneed for heat exchangers in re-circulating wind tunnels is in those usedfor amusement attractions and training facilities, which are oftenoperated near continuously or at least for extended operating hours,unlike testing tunnels. When the wind tunnels are being used asamusement rides or training facilities, the cost and time to build thetunnel become a critical factor in the profitability of the business orviability of the project, while the need to keep the air at acomfortable temperature for paying customers and trainees increases,particularly in warmer climates. Further the heat exchanger must be easyto maintain in terms of both cost and down time, to prevent themaintenance costs of the wind tunnel from becoming excessive. Thereforethe heat exchange mechanism as a whole must be low cost to build andmust be able to be built, installed, inspected, tested, updated and/orreplaced within reasonable time parameters. Further it is important thatany needed repairs must be relatively easy and low cost to perform.

To lower costs it is desirable to be able to use as much off the shelfmaterial as possible for the fluid connections both within the heatexchanger turning vane assembly 201 itself and to the fluid supply.Therefore it is desirable to be able to use standard plastic, rubber,PVC or similarly common plumbing pipes and/or hoses and connectors asmuch as possible. This allows for lower cost materials and easy toreplace pieces when repairs are needed.

Therefore, the connection pieces 202 should function to form a simple,inexpensive, fluid tight connection between the airfoil shape of theturning vane 201 and standard plumbing pipe or hose 204 in the depictedembodiment. The connection pieces 202 must be easy to attach and removefrom the turning vane 201 ends. The connection pieces 202 themselvesshould be low cost to manufacture, in the depicted embodiment they aremanufactured from a two piece injection mold, which significantlyreduces the cost of individual connection pieces 202 to manufacture.

The number and size of the turning vanes in a given heat exchangerturning vane assembly 200 needed in any particular heat exchangerapplication will depend on the airflow speed, heat to be exchanged, andairflow volume of a given tunnel.

FIG. 4 is a perspective view of one end of the heat exchanger turningvane assembly 200 with the turning vane 201 mounted in a rack 215. Inthe depicted embodiment the rack 215 has shaped slots 216 to hold theturning vanes at the appropriate angle and orientation. The racks 215are designed in such a manner that no additional mechanical connectionis required to hold the smooth continuous exterior of the turning vane201 to the rack 215. Side views of the whole heat exchanger turning vaneassembly 200 can be seen in FIGS. 5 and 6 . The horizontal floor of thebottom plenum 108 is indicated by line F. The racks 215 have been shownin a rotated manner for easy of viewing. This should not be taken toindicate that the racks 215 would be mounted in the orientation shown inthe FIGS. 5 and 6 . The appropriate orientation of the rack 215 and theheat exchanger turning vane assembly 200 is also shown in FIG. 1 .

Referring again to FIG. 4 , in the depicted embodiment the inflowingcold water flows through four turning vanes 201 before being carriedaway from the heat exchanger turning vane assembly 200 as warm water.The cold water flows in through inflow pipe 217 and is connected to pipeor rubber hose 204 which is connected to connection piece 202 and thenceto the turning vane 201, labeled A in FIG. 4 . The water flows throughchannels 206, 207 and 208 to the other end, which also has a connectionpiece attached to pipe or rubber hose 204 which in turn connects to Uconnection 218, seen in FIG. 6 , which is like connected to the nextturning vane 201, B, though another U connection 218 to another turningvane 201, C and then again through another U connection 218 to turningvane 201 D and then out through outflow pipe 219. The labels A, B, C andD are purely to indicate the turning vanes 201 being discussed in theflow path to aid the reader in understanding the flow path of thedepicted embodiment. These turning vanes 201 are not different from anyof the other turning vanes 201 discussed herein. This configuration offlowing through four turning vanes is repeated with the remainingturning vanes 201. The inflow pipes 217 are connected to cold watersupply pipe 220 and the outflow pipes are connected to warm waterremoval pipe 221.

The warm water can be used to heat any desired nearby location, eitherby flowing the warm water directly into a water supply line for pool orother location needing warm water, or by having a second heat exchangeron the other end of the line, allowing the heat to be pulled out thewater at the desired location. For example, if the wind tunnel was neara shopping mall or other large recreation center the warm water could beflowed into a heating system for the building and the heat used to heatthe building using standard warm water heat exchange systems. In thosecases the now cooled water could be flowed back to the heat exchangerturning vane assembly 200 to the cold water supply pipe 220, forming alargely closed loop. There would need to be an inlet for more water intothe system to replace water lost to small leaks etc. It may also bedesirable to have a method to flush the system to remove any particlebuild up, such as mineral deposits, that could reduce the efficiency ofthe system

This use of the energy in the heated water to heat some other systemallows some of the energy cost of running the wind tunnel to be offsetby reducing energy costs in another system. This reduces the overallenergy consumption of the whole related complex as the complex is notpaying for cooling the air in the wind tunnel and paying for heatingsome other system.

The flowing of the water through four turning vanes 201 in the depictedembodiment should not be taken as a limitation, fewer passes throughturning vanes 201 or more passes though turning vanes 201 could be used,depending on the application and the cooling needs of any particularinstallation. As mentioned above, other cooling mediums could be used aswell as water in a given installation. No limitation to a particularcooling medium is intended or should be implied.

The connection piece 202 is in FIGS. 7, 8, 9 and 10 . Connection piece202 has a body 235, a pipe connection piece 236 and a bottom surface233. The body 235 has an outer ridge 228 which adds rigidity to theconnection piece and gives it the proper aerodynamic shape. The roundededges of the connection piece 202 are for structural and aestheticreasons. The edges could be square or other configurations as desired.The pipe connection piece 236 has ring 237 extending annularly from itssurface to allow standard hose clamps to attach a standard flexible hoseto the adjacent connection pipe. If desired, a connection pipe could beattached directly to the pipe connection pieces 236 instead of having aflexible hose piece between them. The flexible hose piece allows forflex in the turning vanes 201 caused by the fluid flow or other forcesto be absorbed without causing stress on the fluid pipes.

Referring to FIGS. 7 and 8 , there are four screw holes 230, 231 thatalign with screw bosses 214 a, 214 b respectively on turning vane 201.Screw holes 230 are located near ends 245, 246 of the body 235 and alignwith screw bosses 214 a. Screw holes 231 align with screw bosses 214 band are located on cross members 239, 240, which correspond in locationand general shape to bracing members 209, 210. Cross members 239, 240only extend a limited height H into the interior 241 as seen in FIG. 10. This leaves the majority of the interior 241 of the connection piece202 open to allow for maximum fluid flow. The cross members 239, 240need to be sufficiently rigid to hold the screws when the connectionpiece is held fluid tight against the turning vane 201. The exact heightH of the cross members 239, 240 will depend on the specific application.The cross members 239, 240 divide the bottom surface 233 to form threeopenings 242, 243, 244 that correspond to channels 206, 207 and 208 inthe turning vane 201. This allows the fluid to flow out of the interiorof the turning vane and into the interior 241 of the connection piece202 and then into the pipes and vice versa. The fluid flow from thepipes 217 into the connection piece is split into the channels 206, 207and 208 through the connection piece 202. If a gaseous cooling medium isused, then gas tight connections will be needed, which can be providedwith the appropriate sealing means.

All four screw holes 230, 231 are accessible from the top side of theconnection piece 202, as can be seen in FIG. 7 . This allows aninstaller or repair person to attach or remove the connection piece 202easily and quickly with common tools. The screw holes 231 that attach tothe screw bosses 214 b on the bracing members 209, 210 are required toensure a water tight seal. Screw holes 231 are located within the flowarea of the connection piece 201 so that any leak at the screw headwould be inconsequential. This means that only the other two screw 230locations require a gasket 234 or o-ring to prevent or reduce leakage ofthe fluid from under the screw head. One gasket is used per screwlocation. Unless the turning vane is an extremely small one, the twointernal screw connections are needed to ensure a fluid tightconnection. In such a small turning vane, the bracing members 209, 210might not be needed as well. Recess 232 is formed into the bottomsurface 233 of connection piece 201 correspond to the shape of the endof turning vane 201, so that the connection piece 201 sets over the endof turning vane 201 to allow a water tight seal to be formed. A sealinggasket 234 fits in recess 232 and is shaped to correspond to the bottomof connection pieces 201. The sealing gasket is die-cut from a sheet ofEPDM rubber in the depicted embodiment. Part of the shape of the recess232 is designed to hold the sealing gasket in place while the connectionpiece is being attached to the turning vane. If a gaseous cooling mediumis used, then gas tight connections will be needed, which can beprovided with the appropriate sealing gaskets and sufficiently tightenscrews. If needed the size of the screw holes can be different at eachlocation.

The shape of the connection piece 202 in the depicted embodiment allowsthe connection piece to be formed in a two piece injection mold,allowing the connection pieces 202 to be manufactured at low cost. Inthe depicted embodiment the connection piece is made out of ABS Plasticbut it may also be made from polycarbonate, polypropylene, polyvinylchloride (PVC), nylon and other forms of plastic.

The above system allows a method of cooling comprising the followingsteps:

-   -   flowing a working fluid at a first temperature through a pipe        system to a first heat exchange unit;        -   the heat exchange unit formed of at least one turning vane            having single unit connections pieces at each end of the            hollow turning vane, the connection pieces being removably            attached to the turning vane;        -   the connection pieces having been removably connected to the            hollow turning vanes with mechanical connectors;        -   the heat exchange unit connected to the pipe system such            that fluid can flow from the pipe system into the heat            exchange unit;        -   passing the working fluid from the first heat exchange unit            into a second heat exchange unit;        -   the method further comprising the steps, performed            contemporaneously with the passing steps, of turning air as            the air passes past the hollow turning vanes, and cooling            the air as the air passes past the hollow turning vanes by            transferring heat to the fluid and thereby raising the            temperature of the water from the first temperature to a            second temperature.

The method can further comprise using the heat removed in the firstsystem to be transported to another system and used to heat anothersystem. The method can further comprise returning the now cooled waterto the first system.

While a number of exemplary aspects and embodiments have been discussedabove, those of skill in the art will recognize certain modifications,permutations, additions and sub-combinations therefor. It is thereforeintended that the following appended claims hereinafter introduced areinterpreted to include all such modifications, permutations, additionsand sub-combinations are within their true spirit and scope. Eachapparatus embodiment described herein has numerous equivalents.

The terms and expressions which have been employed are used as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions of excluding any equivalents of thefeatures shown and described or portions thereof, but it is recognizedthat various modifications are possible within the scope of theinvention claimed. Thus, it should be understood that although thepresent invention has been specifically disclosed by preferredembodiments and optional features, modification and variation of theconcepts herein disclosed may be resorted to by those skilled in theart, and that such modifications and variations are considered to bewithin the scope of this invention as defined by the appended claims.Whenever a range is given in the specification, all intermediate rangesand subranges, as well as all individual values included in the rangesgiven are intended to be included in the disclosure.

In general the terms and phrases used herein have their art-recognizedmeaning, which can be found by reference to standard texts, journalreferences and contexts known to those skilled in the art. The abovedefinitions are provided to clarify their specific use in the context ofthe invention.

We claim:
 1. A wind tunnel turning vane heat exchanger in arecirculating wind tunnel comprising: a rack; a plurality of hollowturning vanes formed to allow a fluid to flow through a hollow area ofthe turning vanes, said hollow turning vanes mounted on the rack anddisposed substantially parallel to each other across a plenum of therecirculating wind tunnel; each turning vane having a body extendingbetween two ends, the body having an exterior surface, the exteriorsurface forming a perimeter; connection pieces at each end of the hollowturning vanes to connect the turning vanes to a fluid pipe system; andsaid connection pieces being formed of a single piece and formed toallow a fluid to flow from the hollow area of the turning vanes throughthe connection pieces, said connection pieces connecting in a fluidtight manner to the hollow turning vanes without heat or chemicalbonding; wherein the connection pieces connect to the turning vane atcorresponding connection points on the ends of the turning vanes and theconnection pieces, all of the connecting points being within theperimeter of the turning vane.
 2. The apparatus of claim 1 wherein theconnection points are screw bosses.
 3. The apparatus of claim 1 whereinthe turning vanes have internal cross bracing and the connection piecesconnect to the internal cross bracing with a removable mechanicalconnector.
 4. A wind tunnel turning vane heat exchanger in arecirculating wind tunnel comprising: a rack; a plurality of hollowturning vanes formed to allow a fluid to flow through a hollow area ofthe turning vanes, said hollow turning vanes mounted on the rack anddisposed substantially parallel to each other across a plenum of therecirculating wind tunnel; each turning vane having a body extendingbetween two ends, the body having an exterior surface, the exteriorsurface forming a perimeter; connection pieces at each end of the hollowturning vanes to connect the turning vanes to a fluid pipe system; andsaid connection pieces being formed of a single piece and formed toallow a fluid to flow from the hollow area of the turning vanes throughthe connection pieces, said connection pieces connecting in a fluidtight manner to the hollow turning vanes without heat or chemicalbonding; wherein the turning vanes have internal cross bracing withinthe hollow area thereof and the connection pieces connect to theinternal cross bracing with a removable mechanical connector wherein theconnection pieces connect to the turning vane at correspondingconnection points on the ends of the turning vanes and the connectionpieces, all of the connecting points being within the perimeter of theturning vane.
 5. The apparatus of claim 4 wherein the turning vanes arenon-rotationally mounted with respect to the rack.
 6. The apparatus ofclaim 4 wherein the turning vanes are non-rotationally mounted withrespect to the rack.
 7. A wind tunnel turning vane heat exchanger in arecirculating wind tunnel comprising: a rack; a plurality of hollowturning vanes formed to allow a fluid to flow through a hollow area ofthe turning vanes, said hollow turning vanes mounted on the rack anddisposed substantially parallel to each other across a plenum of therecirculating wind tunnel; connection pieces at each end of the hollowturning vanes to connect the turning vanes to a fluid pipe system; andsaid connection pieces being formed of a single piece and formed toallow a fluid to flow from the hollow area of the turning vanes throughthe connection pieces, said connection pieces connecting in a fluidtight manner to the hollow turning vanes without heat or chemicalbonding; wherein the connection pieces connect to the turning vane atconnection points that are within the hollow area of the turning vaneand the connection points are screw bosses.